The present invention relates to the general field of determining the flow direction of the air that passes through a turbomachine for aviation or terrestrial use.
A turbomachine is typically made up of an assembly comprising in particular an annular compression section for compressing the air that passes through the turbomachine, an annular combustion section disposed at the outlet from the compression section and within which the air coming from the compression section is mixed with fuel so as to be burnt therein, and an annular turbine section disposed at the outlet from the combustion section and having a rotor that is driven in rotation by the gas coming from the combustion section.
The compression section is in the form of a plurality of stages of moving wheels each carrying blades that are disposed in an annular channel through which the turbomachine air passes, and of section that tapers from upstream to downstream. The combustion section is likewise in the form of an annular channel, and the compressed air is mixed therein with fuel in order to be burnt. The turbine section is formed by a plurality of stages of moving wheels each carrying blades that are disposed in an annular channel through which the combustion gas passes.
The flow of air through this assembly generally takes place as follows: the compressed air coming from the last stage of the compression section possesses natural rotary motion with an angle of inclination of about 35° to 45° relative to the longitudinal axis of the turbomachine, which inclination varies as a function of the speed of rotation of the turbomachine. On entering the combustion section, the compressed air is redirected parallel to the longitudinal axis of the turbomachine (i.e. the angle of inclination of the air flow relative to the longitudinal axis of the turbomachine is returned to 0°) by means of a stator. The air in the combustion section is then mixed with fuel so as to ensure satisfactory combustion, and the gas from the combustion continues traveling generally along the longitudinal axis of the turbomachine in order to reach the turbine section. Once there, the combustion gas is redirected by a nozzle so as to present rotary motion having an angle of inclination greater than 70° relative to the longitudinal axis of the turbomachine. Such an angle of inclination is essential for producing an angle of attack suitable for providing the mechanical force for driving the moving wheel of the first stage of the turbine section in rotation.
Such angular variation in the flow direction of the air passing through the turbomachine presents numerous drawbacks. The air which naturally leaves the last stage of the compression section at an angle lying in the range 35° to 45° is successively returned to an axial direction (angle reduced to 0°) on entering the combustion section, and is then redirected to have an angle greater than 70° on entering the turbine section. These successive modifications to the angle of air flow through the turbomachine require intense aerodynamic forces to be produced by the stator in the compression section and by the nozzle in the turbine section, where such aerodynamic forces are particularly harmful to the overall efficiency of the turbomachine.